Note 3 - Revenue From Contracts With Customers (Details Textual)	9 Months Ended
Sep. 30, 2018
Number of Categories in Product Offerings	2
Transferred at Point in Time [Member]
Percentage of Revenue From Goods and Services	86.00%

The percentage of revenue derived from goods and services transferred to customers at a single point in time.

No definition available.

Name:	cui_PercentageOfRevenueFromGoodsAndServices
Namespace Prefix:	cui_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration